so I'm working on making a sensor, and I just got a TI OPA2228 amplifier because the analog signal that I was getting was way too small.
now that i've wired it up, i'm having all kinds of problems. the serial output from arduino goes crazy when it's wired up to my piezo disk. it maxes out at something like 800, and it stays there, fluctuating when I push on it but otherwise stuck at that value. When I let it sit for a while, the TX light on the Arduino starts blinking about once a second, and it seems to be sending some voltage with that frequency.
I wired the amplifier like http://labjack.com/support/ue9/users-guide/188.8.131.52 suggests, using a 200 kohm and 100 kohm for R2 and R1, respectively.
does anybody have any ideas about how to fix this problem, or wire the amplifier in a better way?
a bandpass filter was suggested to me, but i'm a newbie and kind of lost. I also don't want to go out and buy stuff before I know what's going on.